The control of gearboxes of known types used on trucks and lorries is carried out by the driver, according to a complex process, the automatic character of which is obtained by training the driver (declutching, passing to neutral, gearing, coupling, and on occasion, double declutching operation or double action on the accelerator pedal).
The processing device according to the present invention ensures the course of the gear-changing operations automatically, while taking into account all possible cases, as a very good truck or lorry driver would do, without ever committing any mistake.